Microfluidic technologies enable users to culture cells in a more physiological three-dimensional (3D) microenvironment, offering the capabilities of high-resolution real-time imaging, multiple communicating cells types and control over flow and gradients. International Patent Application No PCT/US2009/039434 describes Three-Dimensional Microfluidic Platforms and Methods of Use Thereof. The material used to make these prior art devices is polydimethylsiloxane (PDMS), a moldable silicone that is optically clear and gas permeable. PDMS is commonly used for rapid prototyping with soft lithography processes to produce microfluidic devices. However, PDMS is not an ideal material for cell-based applications for reasons outlined in detail by Beebe et al. in Lab Chip, 2012, 12, 1224-1237. In brief, some of the disadvantages include:                PDMS is a permeable material prone to the bulk absorption of hydrophobic compounds—Biological assays investigating hydrophobic drugs/proteins will be affected, as their effective concentration would be lowered by bulk absorption.        PDMS is prone to evaporation—The water vapour permeability of PDMS is a disadvantage in microfluidic devices where the volume of culture media used is small. Evaporation may cause osmolarity shifts and affect cell behaviour.        PDMS will recover its hydrophobicity—PDMS is normally hydrophobic and is treated with plasma to increase the hydrophilicity of the surface. A hydrophilic surface facilitates specific processes in microfluidics, such as surface functionalization and microchannel filling. However, plasma-treated PDMS surfaces recover their hydrophobicity due to the diffusion of polymer chains from the bulk to the surface. Users then have to repeat plasma treatment prior to use; besides the inconvenience, many users may not have access to plasma chambers.        PDMS is unsuitable for high volume manufacturing—The manufacturing cycle time for PDMS is unacceptably long due to its lengthy curing and processing time.        
The present invention was developed with a view to providing a three dimensional microfluidic platform made of plastics material that is less susceptible to the problems of the prior art devices made of PDMS. The microfluidic platform of the present invention may also incorporate a number of other advantageous features that improve its functionality.
References to prior art documents in this specification are provided for illustrative purposes only and are not to be taken as an admission that such prior art is part of the common general knowledge in Singapore or elsewhere.